Should I update Blender?
Blender as no builtin automatic update system at the moment, you always have to download and manually install new versions.
They are for the most part backwards compatible except for major versions like the jump between 2.49 to the 2.5 series, or between 2.79 and the 2.8 series. Apart from some small additions or changes you should always be able to open your files without problems on newer versions unless stated in the release notes.
If there is no particular functionality from the dropped features list you specifically need, and if your hardware is compatible with newer versions, it is always advised to upgrade, unless you are in the middle of some critical project, commercial production work, or a complex scene, in which case you are advised to finish your work before messing with the software installation.
New versions can bring bugs and introduced regressions or some time have issues with newer driver and hardware.
If you want something close to an auto update system you can try the Steam version of Blender.